Ruby is not in a spectrum of "highly efficient" languages. It's interpreted, pretty slow and not concurrent. Java is very good for like 99% of cases, and it's much faster to work with than Rust. But, if you really want to be "close to the metal", Rust is your language of choice. It does not have garbage collector. Memory safety is guaranteed by the language itself. This is great, but the cost of that is pretty steep learning curve. But it's still a lot of fun when you get a grip of it.